The efficient extraction of the metals is considerably simplified by totally stripping or separating all the materials occurring in the ores. During the process of smelting the metals, it cannot be avoided that molten metals (e.g. Fe and Cu) get into the slag, due to the melting process, and these are likewise difficult to recover.
Numerous ferrous and non-ferrous metals are to be found in the slags and ashes of thermal waste recovery, as well as the slags of metal production, which are integrated into mineral slags in pure form or heavily scaled. It is only possible to efficiently recover such metals from material conglomerates if these metals are released or separated from their compounds/scaling in such a way that they can subsequently be isolated from the material flow by magnets or non-ferrous metal separators.
According to the prior art, such slag is shredded with conventional hammer and impact mills, and subsequently fed to magnets and non-ferrous metal separators.
Using hammer and impact mills, it is possible, and also efficient, to release and recover metals having a particle size of over 20 mm. In regard to the release of smaller metal particles with such mills, very small gap clearances need to be set, for example under 20 mm, which would lead to a great increase in the mill crushing at the expense of the impact crushing. Said mill crushing would have the consequence that soft non-ferrous metals would be ground in such a way that they could no longer be separated using a non-ferrous metal separator. Thus, it is only possible to recover small metal particles existing in the slag in a pure form with the comminuting devices forming the prior art to a limited extent.
EP 2 529 835 A2 shows a comminuting device with features including features including a comminution chamber having a supply end and a discharge end, which comminution chamber is enclosed by a circular cylindrical and has at least two portions in succession in the axial direction, in each of which at least one rotor is arranged coaxially with the comminution chamber, each rotor having a rotor shaft and having striking tools which extend substantially radially into the comminution chamber at least during operation, the rotors having opposite directions of rotation in at least two successive portions. The comminution chamber also has deflection ribs (48) arranged annularly on the inside of the comminution chamber wall at axial intervals and/or the radius of the comminution chamber wall (42) increasing from top to bottom.